Rowan's Sampler Afghan is designed to be made with Worsted Weight Yarn, using a size I or J hook. I am currently working up 2 afghans as I work out the patterns for each square. I selected Red Heart Super Saver as a typical, inexpensive worsted weight acrylic yarn, similar to many other brands. I also selected some Caron Simply Soft as it is softer than most typical acrylic yarn, which is nice to work with and softer for babies. While I generally prefer working with more natural fibers, most NICUs only want acrylic or possibly cotton blankets.
Your hook size will depend on the gauge square, but that is for another post. I am using a J-hook with the Red Heart yarn, but if your gauge is looser or tighter you can switch to an I or a K size hook. I am using a K-hook with the Simply Soft to get the same size squares because the softer yarn works up a bit tighter than the regular, denser acrylic yarns.
Multi-colored "Ombre" yarns can be fun to work with. But for this project I recommend sticking with solid colors to show off your fancy stitches. I am making both of my samples using 2 coordinating colors (aqua/mint and mauve/lavender) and plan to sew them together alternating the colors. If you have a multi-colored yarn you just have to use, make the plainer squares with that yarn and choose a complementary solid for the more textured squares. Another option is using up your scrap balls making each square a different color, which can be tied together by using the same color for the single crochet edging which goes around each square.
How Much Yarn
I have not completed all of the squares for a sample quite yet, but I believe it will take about 20oz. of yarn for the whole blanket. For a 2 color blanket I need two 7oz. skiens of each color for a total of 4 skiens. If you make the entire pattern in just one color, which would also look lovely with so many different stitches, I believe only 3 skiens would be enough.
Where To Get Yarn
I always like to support Local Yarn Shops (LYS). They have beautiful yarns you cannot get at the big box stores and are a dying breed. The only one left in our area is It's A Crewel World in Washougal (though I bhave heard the name is chsnging with a new owner). But for charity projects quantity is often more important than quality, so the bigger stores are the place to go to get coupons and sales on already cheap yarn. This is Customer Appreciation Week at Michael's. You can get a coupon for 20% off your entire purchase here, just remember to print it out before you go in to the store. I am planning to stock up on Red Heart, Pound of Love, Simply Soft, and Vanna's Choice yarns in lots of lovely babyish colors (not just pastels to have on hand for locals wanting to join the Crochet Along.